Construction for electronic oven appliances

ABSTRACT

An electronic microwave oven having a unitary cast door frame to which rearwardly extending channel members are attached for the support of a component tray which forms the oven roof and supports relatively heavy electronic oven components required for the generation of microwave energy. The channel sections are hollowed to permit insertion of the user&#39;&#39;s fingers for lifting, and the hollows extend to the rear of the oven unit to allow the unit to be received by a pair of horizontal parallel support bars in a built-in wall installation. The escape of microwave energy is prevented by providing inturned flanges for the sidewalls, component tray and oven floor portions, and the oven door is sealed by means of a compressible annular metallic seal which assures a continuous electrical connection between the door and door frame.

United States Patent Inventor Egbert M. Tingley Kankakee, Ill.

Appl. No. 858,793

Filed Sept. 17, 1969 Patented Apr. 27, 1971 Assignee Roper Corporation Kankakee, Ill.

CONSTRUCTION FOR ELECTRONIC OVEN APPLIANCES 5 Claims, 8 Drawing Figs.

US. Cl 219/ 10.55, 126/39, 312/264, 219/1075 Int. Cl 1105b 9/00, 1105b 5/00 Field of Search 219/1055; 126/39, 39 (B), 39 (C); 312/257 (SK), 264,138

References Cited UNITED STATES PATENTS 2,295,915 9/ 1942 Ring 126/398 11/1964 Pollock et a1.

3,339,054 8/1967 Deaton 219/1055 3,430,023 2/1969 Tingley 219/1055 3,443,050 5/ 1969 Puschner 2 1 9/ 10.55

Primary Examiner-J. V. Truhe Assistant ExaminerL. H. Bender Attorney-Wolfe, Hubbard, Leydig, Voit and Osann ABSTRACT: An electronic microwave oven having a unitary cast door frame to which rearwardly extending channel membets are attached for the support of a component tray which forms the oven roof and supports relatively heavy electronic oven components required for the generation of microwave energy. The channel sections are hollowed to permit insertion of the users fingers for lifting, and the hollows extend to the rear of the oven unit to allow the unit to be received by a pair of horizontal parallel support bars in a built-in wall installation. The escape of microwave energy is prevented by providing intumed flanges for the sidewalls, component tray and oven floor portions, and the oven door is sealed by means of a compressible annular metallic seal which assures a continuous electrical connection between the door and door frame.

- Patenfgd A ril 27, 1971 3,576,417

4 Sheets-Sheet 1 @4 www/ a CONSTRUCTION FOR ELECTRONIC OVEN APPLIANCES DESCRIPTION OF THE INVENTION The present invention relates to oven constructions, and in its principal aspect Concerns an oven construction particularly adapted for electronic microwave ovens in whichrelatively heavy electronic heat-generating components must be contained and supported in close proximity to the oven space.

A principal object of the present invention is to provide an improved construction for electronic oven appliances in which relatively heavy heat-generating components may be rigidly supported adjacent the oven space in a structure which is resistant to twisting and warping, yet which retains the advantages of relatively simple, inexpensive and lightweight construction.

Another object is to provide such an oven construction in which the electronic heat-generating components are supported adjacent the oven space and protected by a removable cover which may be taken off for access without disassembling the oven itself.

A further object is to provide an oven construction particularly adapted for electronic microwave ovens in which a reliable electronic seal is maintained throughout the interior of the oven space, with a rigid front door frame containing a hinged door which forms a continuous electrical path with the rest of the oven structure when in the closed position.

A more detailed object is to provide an oven construction for electronic oven appliances in which a relatively massive front frame coplanar control panel are joined to a pair of chassis-forming channel members to form a rigid external frame structure which is capable of locating and supporting a component tray capable of carrying relatively heavy electronic heat-generating components, as well as relatively lightweight oven sidewalls and an oven floor and rear closure.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIG. 1 is a front perspective of an electronic microwave oven appliance exemplifying the present invention;

FIG. 2 is an enlarged fragmentary side elevation taken in the plane 22 of FIG. 1 showing the oven door in its open (dashed lines) and closed positions;

FIG. 3 is a further enlarged fragmentary section taken in the plane3-3 of FIG. 2;

FIG. 4 is a section similar to FIG. 3 tal ren in the plane 4-4 of FIG. 2;

FIG. 5 is a complete side elevation in section taken in the plane 5-5 of FIG. I;

FIG. 6 is a fragmentary plan view in section taken in the plane 6-6 of FIG. 5;

FIG. 7 is a front elevation in partial section of the oven of FIG. I; and

FIG. 8 is a plan view in section taken in the plane 8-8 of FIG. 1.

While the invention is shown in connection with a particular exemplary embodiment, it should be understood that the invention is not to be. confined to the particular embodiment shown and illustrated herein, but is on the'c'ontrary applicable to' any electronic oven appliance in which a rigid, attractive, lightweight oven construction is desired, coupled with the advantages-of a reliable electrical seal between the components forming the oven space and a rigid support for relatively heavy electronic heat-generating components immediately adjacent the oven space.

Turning now to the drawings, there is shown in FIG. 1 an exemplary microwave oven embodying the advantageous features of the present invention. The oven has as its front portion a door frame 10 containing a hinged oven door 11 which swings outward by means of a handle 12. Above the door frame 10 is an upstanding vertical control panel 13 having a control switch 14 for operating the oven by initiating a timed heating cycle of predetermined duration. Visible at each side of the oven is a rearwardly extending channel section 15, below which extends oven sidewalls l6 and above which is a cover means 17 enclosing the electronic heat-generating components within.

As aprincipal feature of the invention, the relatively heavy electronic heat-generating components are rigidly mounted on a horizontal chassisstructure which is itself secured to a frame-fonning portion of the oven, which serves to locate and rigidly support certain additional panel members which form the actual oven enclosure. As best shown in FIG. 7, the channel members 15 extendhorizontally for the length of the oven sides, being secured to the sidewalls 16 by fasteners 18 adapted to engage T-slots 19 provided in the channel members 15 for this purpose. Also secured to the channel members 15 by the fasteners 18 is a component tray 20which supports the various electronic heat-generating components directly above the oven space. Above the channel members 15' and component tray 20 is the cover 17, having flanges 21 which are slidably received in corresponding slots in each channel member 15. The channel members 15 are preferably made from an extruded material such as aluminum or zinc alloy, with the various slots formed in the extruding process.

The electronic heat-generating components supported by the component tray 20 are of conventional construction as generally practiced in the microwave oven art. A transformer 22 converts ordinary household alternating current to a high voltage which is converted in a magnetron tube 23 into microwave radio energy. These and other electronic components are conveniently supported on upstanding chassis members 24 which mount directly to the component tray 20 and provide additional stiffness to the assembly. The radio energy is then directed through a waveguide assembly 25 and enters the oven cavity by means of cutout portions 26,27 (FIG. 8) of predetermined size. The component tray 20 is also provided with perforated openings 28 through which an oven light 29 may provide internal illumination for the oven.

A blower 30 draws air through a group of louvres 31 at the rear of the cover 17, and after passing through a filter 32 the air passes over the electronic components for'cooling purposes. The air is then exhausted from the component area through perforations 33 in the component tray 20 and through a plastic cover 34 attached to the underside of the component tray 20 from which it enters the oven cavity through an opening in the rear of the plastic cover 33. From the oven cavity the air then exits through a group of spaced perforations 35 in the door 11.

A motor 36 is provided above the waveguide 25 which drives a three-bladed metal stirrer 37 within the plastic cover 33, with the individual blades of the stirrer 37 passing over the cutout portions 26,27'where the microwave energy enters the oven space from the waveguide 25. This device prevents standing waves from building up which would interfere with uniform heating within the oven space.

The actual oven cavity is defined by the sidewalls 16 previously mentioned, a rear closure 38, and a floor 40 to which individual rubber or plastic feet 41 are attached. A cooking surface is formed within the oven cavity by a slab of heat-resistant ceramic material 42 which rests at the rear of the cavity on lugs 43, and at the front on a shelf 45 fonned in the door frame I0. The door frame 10 is preferably made as a unit from a casting or the like, having parallel top and bottom members connected by parallel side members to form a rigid rectangular unit, and includinga forward-facing flange 46 extending around the bottom, sides and top of the door frame 10 which is adapted to receive and surround the oven door 11 when in a closed position. 7

It is a further feature of the invention that the sidewalls 16, the floor 40, and the component tray 20 are all provided with flange portions 47 (FIGS. 5 and 8) turned inwardly toward the oven space which mate flush with a corresponding portion of the door frame 10, providing a reliable electrical seal which prevents the escape of microwave energy from the interior of the oven. Fasteners 48 secure the sidewalls 16, floor 40 and component tray 20 to the door frame 10. Each fastener 48 is attached to a protruding lug or embossment 49 cast into the door frame 10, with short sections of channel material 50 being used to resiliently clamp the various members against the door frame to prevent loosening.

The attractive massive front appearance of the oven is in large part due to the combination of the unitary cast door frame 10 and the control panel 13 which is desirably made of a similar cast construction. The control panel 13 carries the control switch 14 which attaches to a timer means 51 within the component enclosure formed by the cover 17.

The door 11 also includes a cast rim 52 construction for stiffness, to which are attached a perforated inner panel 54 (having perforations 35 for the exit of cooling air) and a decorative bezel 55. The door hinge 53 is preferably of the piano-hinge type in order to provide the maximum amount of electrical contact between the door 11 and door frame 10. The door handle 12 extends through the bezel 55 and rotates a latch member 56 for locking the door 11 to the door frame 10 and for actuating a door bolt switch 57. The switch 57 is used to prevent the energization of the microwave heat-generating components when the door 11 is open. For added security, a small magnet 58 is located within the door 11 and a magnetically actuated switch 60, such as a reed switch, is placed in series with the door bolt switch 57 to provide an additional safeguard against defeat of the door bolt switch 57.

The electrical microwave seal between the door 11 and the door frame 10 is perfected by use of a compressible annular metallic seal 61 of mesh construction, having a flange or tail portion which is secured to the bezel 55 by spot welds 62 which also serve to attach the bezel 55 to the door inner panel 54. When the door is closed, the mesh seal 61 flattens slightly and engages the outer surface of the door frame 10 over a relatively wide area, providing sufficient electrical contact to positively prevent any microwave energy from escaping the oven space.

A limit for opening of the door 11 as well as a support when in the open position is furnished by a pair of guide bars 63 pivoted at their upper ends to the oven door frame 10, and having elongate slots in which a door pin 65 is slidably received.

Advantageously, the structure of the present invention allows the relatively heavy electronic heat-generating components such as the transformer 22, blower 30, motor 36, and other components not specifically identified but shown generally in FIGS. 5, 7 and 8, to be mounted directly on the component tray which-is in turn supported immediately on either side by the extruded channel members 15 and at the front by the cast door frame 10. The greatest amount of component mass is therefore concentrated in the immediate area between the channel members 15 so that the entire oven may be easily lifted and handled by simply placing the fingers within the hollowsv conveniently provided by the channelshaped longitudinal hollow in each of the channel members 15. The channel members 15 also have a constant cross section from front to back, being open at the rear to define an open-ended slot or groove on each side of the oven. This feature allows the oven to be slid onto a pair of spaced parallel support bars (not shown) much as a drawer slides into a cabinet. Since the support is thus provided at the point where the relatively heavy microwave components are located, the oven is securely supported and balanced in such an installation while retaining advantages of easy removal should it be desired to carry it toanother location.

As an additional advantage, the relatively heavy cast door frame 10 combines with the rigid extruded channel members 15 to provide a strong frame structure for the rest of the oven. To this frame structure the door 11 is hinged so that opening and closing of the door 11 will have virtually no effect on the rest of the oven structure. Without the advantageous structure provided by the invention the relatively lightweight sheet metal walls 16, floor 40 and rear closure 38 would be incapable of adequately withstanding the forces encountered during normal transport or operation without bending or distorting. By linking the heavy cast door frame 10 and extruded channel members 15, however, the entire oven structure is locked into a rigid unit which is capable of withstanding relatively large forces without twisting, warping or in any way affecting the integrity of the electrical seal between the various members forming the oven cavity, which is of great importance in preventing escape of microwave energy during oven operation.

lclaim:

1. in an electronic oven assembly the combination comprising, a vertical front door frame having a door opening, said door frame being of relatively massive rigid construction with each side being of L cross section forming a forwardly projecting edge portion and a moimting portion extending inwardly at right angles thereto to form a mounting surface, an oven door hinged to the frame for closing the door opening, a boxlike oven enclosure including relatively thin metal walls having their front edges bent inwardly to form a flange overlying the mounting surface of the door frame, said door frame having integral threaded embossments spaced along the mounting surface and said flange having registering openings for receiving the embossments, and threaded clamping means screwed into said embossments and engaging the flange at spaced points so that the flange is held intimately against the mounting surface for rigidification of the enclosure and to prevent escape of microwave energy between the enclosure and frame.

2. In an electronic oven assembly the combination comprising a vertical front door frame having a door opening, the door frame being of relatively massive rigid construction with each side being of L cross section forming a forwardly projecting edge portion and a mounting portion extending inwardly at right angles thereto to form a moimting surface, an oven door hinged to the frame for closing the door opening, a boxlike oven enclosure including relatively thin metal walls having their front edges bent inwardly to form a flange overlying the mounting surface of the door frame, means for securing the flange to the mounting surface, relatively massive channel members extending from front to back along the upper edges of the boxlike oven enclosure and defining horizontally extending outwardly facing grooves, a component tray supported by the channel members and front door frame, means mounted on the component tray for generating radiant energy within the oven space, and a boxlike cover for the component tray conforming to the shape of the oven enclosure and secured along its lower lateral edges to the upper portion of the channels.

3. The combination as claimed in claim 2 in which both channel members are open at the rear to permit sliding supportive engagement by a pair of horizontally spaced parallel support bars.

4. The combination as claimed in claim 2 in which the door frame is provided with an upward extension enclosing the front of the boxlike cover and having control elements mounted thereon for control of the components in the component tray.

5. In an electronic oven assembly, the combination comprising a vertical front door frame having a door opening, said door frame being of relatively massive rigid construction with each side being of L cross section forming a forwardly projecting edge portion and a mounting portion extending inwardly at right angles thereto to form a mounting surface, a door hinged to the frame for closing the door opening, a boxlike oven enclosure of relatively light metal having an inwardly bent flange secured to the mounting surface, a component tray above the oven enclosure having means for generating radiant energy in the oven space, a boxlike component enclosure of light metal superimposed above the component tray and conforming to the top of the oven enclosure, and a pair of relatively massive channel members secured to the upper comers of the door frame and extending rearwardly therefrom, such channel members being interposed between the enclosures and rigidly secured to each of them for providing rigidification in a plane perpendicular to the rigid door frame and for defining horizontal finger-engagable grooves between the enclosures for lifting and mounting of the oven assembly. 

1. In an electronic oven assembly the combination comprising, a vertical front door frame having a door opening, said door frame being of relatively massive rigid construction with each side being of L cross section forming a forwardly projecting edge portion and a mounting portion extending inwardly at right angles thereto to form a mounting surface, an oven door hinged to the frame for closing the door opening, a boxlike oven enclosure including relatively thin metal walls having their front edges bent inwardly to form a flange overlying the mounting surface of the door frame, said door frame having integral threaded embossments spaced along the mounting surface and said flange having registering openings for receiving the embossments, and threaded clamping means screwed into said embossments and engaging the flange at spaced points so that the flange is held intimately against the mounting surface for rigidification of the enclosure and to prevent escape of microwave energy between the enclosure and frame.
 2. In an electronic oven assembly the combination comprising a vertical front door frame having a door opening, the door frame being of relatively massive rigid construction with each side being of L cross section forming a forwardly projecting edge portion and a mounting portion extending inwardly at right angles thereto to form a mounting surface, an oven door hinged to the frame for closing the door opening, a boxlike oven enclosure including relatively thin metal walls having their front edges bent inwardly to form a flange overlying the mounting surface of the door frame, means for securing the flange to the mounting surface, relatively massive channel members extending from front to back along the upper edges of the boxlike oven enclosure and defining horizontally extEnding outwardly facing grooves, a component tray supported by the channel members and front door frame, means mounted on the component tray for generating radiant energy within the oven space, and a boxlike cover for the component tray conforming to the shape of the oven enclosure and secured along its lower lateral edges to the upper portion of the channels.
 3. The combination as claimed in claim 2 in which both channel members are open at the rear to permit sliding supportive engagement by a pair of horizontally spaced parallel support bars.
 4. The combination as claimed in claim 2 in which the door frame is provided with an upward extension enclosing the front of the boxlike cover and having control elements mounted thereon for control of the components in the component tray.
 5. In an electronic oven assembly, the combination comprising a vertical front door frame having a door opening, said door frame being of relatively massive rigid construction with each side being of L cross section forming a forwardly projecting edge portion and a mounting portion extending inwardly at right angles thereto to form a mounting surface, a door hinged to the frame for closing the door opening, a boxlike oven enclosure of relatively light metal having an inwardly bent flange secured to the mounting surface, a component tray above the oven enclosure having means for generating radiant energy in the oven space, a boxlike component enclosure of light metal superimposed above the component tray and conforming to the top of the oven enclosure, and a pair of relatively massive channel members secured to the upper corners of the door frame and extending rearwardly therefrom, such channel members being interposed between the enclosures and rigidly secured to each of them for providing rigidification in a plane perpendicular to the rigid door frame and for defining horizontal finger-engagable grooves between the enclosures for lifting and mounting of the oven assembly. 